Basic and Diluted Earnings per Share - Computation of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Earnings Per Share [Abstract]
Net income attributable to SS&C common stockholders	$ 760.5	$ 607.1	$ 650.2
Shares attributable to SS&C:
Weighted-average common shares outstanding - used in calculation of basic EPS	246.4	248.3	254.0
Weighted-average common stock equivalents – stock options and restricted shares	7.4	6.2	8.0
Weighted-average common and common equivalent shares outstanding – used in calculation of diluted EPS	253.8	254.5	262.0
Earnings per share attributable to SS&C common stockholders- Basic	$ 3.09	$ 2.45	$ 2.56
Earnings per share attributable to SS&C common stockholders - Diluted	$ 3	$ 2.39	$ 2.48